I had heard this explanation before - children used be an economic benefit, and now they are an economic burden. But this goes a little deeper.

Basically, there is a massive social transformation from a "traditional" society based around kinship groups and reciprocity, to an industrial one sustained by the nation-state and based around money transactions and wage labor. In a traditional society based around subsistence farming, children are a net economic benefit both as workers and to take care of aging parents. In a industrial society, they are a burden as they are not productive until they are older, and parents must pay for everything until that time. So the parents "produce" goods that the society needs (new worker bees), and must foot the bill.

In a traditional society, children are "owned" by the family - wider society butt out, thank you very much. In a post-agricultural industrial society, children are the property of the nation-state and must be turned into productive adults who fit into the industrial system. When we were initially transitioning into that industrial system, the burden for that transition was borne by the nation-state (since most families had little money) by requiring universal education and paying for it mainly by taxing land, which is how schools are still funded today. That made sense when land was productive and owned by businesses, but in a society based on home ownership, it does not work so well.

In any case, the government paid for mass education, which was yet another way capitalism is entirely a creation of governments and not the "free" market. The U.S. used the Prussian Educational system as a model to train children like Pavlov's dogs to sit still, be on time, accept discipline and obey authority, along with basic reading and writing. It banned child labor, and children became drags on their parents until adulthood, arbitrarily defined as age 18. Childrens' ability to work is entirely based on their academic training; their physical abilities are useless (we no longer have chimney sweeps). Thus, children are economically dead weight until they acquire all these high-level cognitive skills.

The children are then transformed (broken?) into the workers that the capitalists need and the soldiers that the government needs. The state has claims on workers for taxes and for military conscription. It may surprise some that the reason we don't have more children is because they are a collectivist good in our society that supposedly celebrates absolute individualism and lack of any social obligations to the wider society as the special sauce that makes capitalism work and creates prosperity. It just shows how the simplistic left/right narrative does not describe the world that we live in.

Now, we see that the economic burden of turning children into economically valuable productive adults has been shifted from business and the state, and onto the backs of the families and children themselves! Now "college is the new high school," and anyone who does not complete a graduate degree is blamed for their own poverty and unemployment. This has led to the stark class divisions of today - if mommy and daddy haven't been socking away tens of thousands of dollars since birth for your education past high school, get ready to either work in fast food or be a debt donkey the rest of your life. Education funding is either a lottery system (scholarships), military conscription, or based around the Matthew Principle - to those that have more will be given, but those who have little will find even that is taken away.

It's worth pointing out that in traditional societies, everyone used to work, and there was no concept of "employment" or "jobs". Work was something that everybody did, so the "employment rate pretty much included everybody. Today, "workers" are arbitrarily defined as 20-65, and yet we still have an unemployment crisis! Note how they keep dragging up the low end of that scale as education requirements keep ratcheting up (primarily to service the education-industrial complex, as most of this so-called education is useless busywork and jumping thorough arbitrary hoops)

Also not noted is the fact that infant mortality has declined, and that having 1-2 children in the past was as good as having none in the high mortality world after the Neolithic revolution.

But the fertility decline is not merely the product of a price effect - of people having fewer children because children are more costly. Children are not normal goods...or even inferior goods...they become not goods at all, but rather bundles of claims on their parents. ..Before the fertility decline, resources flowed from children to parents; after the transformation, resources flowed from parents to children.

In each country, before the demographic transition, children were essentially the property of their parents. Their labor could be used for the parents' good, and they were accustomed to strict and austere treatment. Parents had claims not only to their children's labor in childhood, but even to their wealth in adulthood. To put it crudely, marrying a wife meant buying a slave factory, and children were valuable slaves.

After the transition, mediated by mass education, children were transubstantiated into persons. Their individual status increased, and parents no longer had a culturally recognized claim on their labor. Children's culturally supported entitlements increased, including not only food and clothing, but also study and play time. Their relationship with their parents became more egalitarian and friendly, their treatment less strict.

But children do not exactly own themselves in the present situation: the government has claims on their future earnings, through taxation and other mandatory payments (and, increasingly, education loans). In essence, mass education is a communist transformation: individually-owned "goods" (children) are brought under national ownership, and returns from children flow to the country as a whole (through tax-based entitlement programs), rather than individually to their previous "owners." When farms are communally owned, production suffers and famine results; when children are communally "owned," fertility decline results.

There is another, related shift in the direction of resource flow during this time: resources (including labor) stop flowing from wives to husbands, and instead flow from husbands to wives, as a result of Western-style female liberation. This trend is also a result of education, and amplifies the trend toward low fertility.

So why did people used to have children? It's hard for us even to imagine, but children used to be valuable - they used to be much more like slaves or farm animals, which are both very valuable. They were also treated much more like slaves, with patriarchs (at least) maintaining distance from children...

Indeed, even in the early Industrial Revolution, children worked. We think of that as abnormal now, but in fact it is our own situation which is abnormal in a historical context. Of course children didn't do nasty, dirty and toxic stuff in an agricultural situation. The early Industrial Revolution apologist Andrew Ure referred to children as "lively elves:"

"I have visited many factories, both in Manchester and in the surrounding districts, during a period of several months, entering the spinning rooms, unexpectedly, and often alone, at different times of the day, and I never saw a single instance of corporal chastisement inflicted on a child, nor indeed did I ever see children in ill-humour. They seemed to be always cheerful and alert, taking pleasure in the light play of their muscles,-enjoying the mobility natural to their age. The scene of industry, so far from exciting sad emotions in my mind, was always exhilarating. It was delightful to observe the nimbleness with which they pieced the broken ends, as the mule-carriage began to recede from the fixed roller-beam, and to see them at leisure, after a few seconds' exercise of their tiny fingers, to amuse themselves in any attitude they chose, till the stretch and winding-on were once more completed. The work of these lively elves seemed to resemble a sport, in which habit gave them a pleasing dexterity. Conscious of their skill, they were delighted to show it off to any stranger..."

[C]hildren were valuable in other ways, and mass education interfered with all of them, not just their economic contribution. To return to the central analogy, slaves are valuable for many reasons besides their ability to produce more than they consume: they may help with childcare, provide companionship, and serve as status goods (from the point of view of peers). The type of companionship slaves provide is relevant: they are low-status beings, and with their servile behavior they provide the owner with constant reminders that he is powerful and high-status. A slave of this type's mere presence represents a type of consumption on the part of the owner, similar to the consumption of entertainment.

The practice of apprenticeship and child servitude suggests that many children even in complex societies contributed positive economic value at a young age.

But there is another way in which children used to contribute: they gave a parent his status as a free adult, and marriage and children were the only path to free adulthood...

In summary, children used to be:

hard working and helpful, especially at the work of raising a large family;

self-sufficient at an early age;

submissive to adults;

the only path to adult status

Education, specifically Western education promoting democratic values, interferes with children's work and their parents' expectations for their work. It makes them more dependent on their parents, and makes them less likely to be servile and submissive to parents. And education itself provides an alternate means of achieving adult status other than having children. In the presence of these conditions, the demand for children is apparently low.

Now you might ask the question, which is better, and the article is silent on this point. I can see things either way. No doubt the treatment of children as little slaves led to a lot of mistreatment and abuse in some circumstances. Today, the state feels a right to intervene in situations of abuse and neglect, which surely prevents some of the more horrible situations that would have resulted in the past. On the other had, the invention of this period of "childhood" where kids are owned by the state, institutionalized, and economically non-productive has had negative consequences too. Now children are marketed to relentlessly to hector their parents to spend, and all adults are held up to as hopelessly out-of-date fuddy-duddies and objects of ridicule. No doubt this leads to infatilism of our culture and the celebration of childhood as somehow "special." Of course, slowing population growth is a good thing, but I wonder if this is the best way to accomplish that.

Of course, some people have lots of children no matter what the incentives. In this article from a ways back, Philip Longman makes the point that the people who buck the above economic calculus tend to be those reject the modern world such as religious cults and fundamentalists. And he echoes a common fear that we are disincentivizing the most educated people from having children at all with the ridiculous burdens we put on them - years of expensive education, chaotic work and school schedules, and no support for child care (in the U.S. anyway).

Some biologists now speculate that modern humans have created an environment in which the "fittest," or most successful, individuals are those who have few, if any, children. As more and more people find themselves living under urban conditions in which children no longer provide economic benefit to their parents, but rather are costly impediments to material success, people who are well adapted to this new environment will tend not to reproduce themselves. And many others who are not so successful will imitate them.

So where will the children of the future come from? The answer may be from people who are at odds with the modern environment -- either those who don't understand the new rules of the game, which make large families an economic and social liability, or those who, out of religious or chauvinistic conviction, reject the game altogether.

Today there is a strong correlation between religious conviction and high fertility. In the United States, for example, fully 47 percent of people who attend church weekly say that the ideal family size is three or more children, as compared to only 27 percent of those who seldom attend church. In Utah, where 69 percent of all residents are registered members of the Church of Jesus Christ of Latter Day Saints, fertility rates are the highest in the nation. Utah annually produces 90 children for every 1,000 women of childbearing age. By comparison, Vermont -- the only state to send a socialist to Congress and the first to embrace gay civil unions -- produces only 49.

Does this mean that the future belongs to those who believe they are (or who are in fact) commanded by a higher power to procreate? Based on current trends, the answer appears to be yes. Once, demographers believed that some law of human nature would prevent fertility rates from remaining below replacement level within any healthy population for more than brief periods. After all, don't we all carry the genes of our Neolithic ancestors, who one way or another managed to produce enough babies to sustain the race? Today, however, it has become clear that no law of nature ensures that human beings, living in free, developed societies, will create enough children to reproduce themselves. Japanese fertility rates have been below replacement levels since the mid-1950s, and the last time Europeans produced enough children to reproduce themselves was the mid-1970s. Yet modern institutions have yet to adapt to this new reality.

Current demographic trends work against modernity in another way as well. Not only is the spread of urbanization and industrialization itself a major cause of falling fertility, it is also a major cause of so-called diseases of affluence, such as overeating, lack of exercise, and substance abuse, which leave a higher and higher percentage of the population stricken by chronic medical conditions. Those who reject modernity would thus seem to have an evolutionary advantage, whether they are clean-living Mormons or Muslims, or members of emerging sects and national movements that emphasize high birthrates and anti-materialism.

The problem is that even as modern societies demand more and more investment in human capital, this demand threatens its own supply. The clear tendency of economic development is toward a more knowledge-based, networked economy in which decision-making and responsibility are increasingly necessary at lower levels. In such economies, however, children often remain economically dependent on their parents well into their own childbearing years because it takes that long to acquire the panoply of technical skills, credentials, social understanding, and personal maturity that more and more jobs now require. For the same reason, many couples discover that by the time they feel they can afford children, they can no longer produce them, or must settle for just one or two.

Meanwhile, even as aging societies become more and more dependent on the human capital parents provide, parents themselves get to keep less and less of the wealth they create by investing in their children. Employers make use of the skills parents endow their children with but offer parents no compensation. Governments also depend on parents to provide the next generation of taxpayers, but, with rare exception, give parents no greater benefits in old age than non-parents.

Indeed, the burdens of having children just keep rising, especially thanks to our winner-take-all social systems:

When the sociologist Marianne Cooper interviewed affluent Silicon Valley couples for her new book, “Cut Adrift: Families in Insecure Times,” she was struck by the anxiety they expressed about their retirement prospects, and especially about how to provide their children with the skills, résumés and entrepreneurial personality traits they believe are now needed to succeed in a “winner-take-all” job market.

College-educated parents have increased the time they spend with their children at twice the rate of other Americans since the 1990s, much of it devoted to chauffeuring kids to games, camps and other activities. But these frenetic schedules are stressful and may interfere with the time couples have to spend alone, which is important to marital quality. This could be dangerous down the road, because divorce rates among couples over 50 have more than doubled since 1990, and because the protective factor of high education is not as great in late-life divorces. According to Susan L. Brown and I-Fen Lin, sociologists at Bowling Green State University, the divorce rates of college graduates over 50 are almost as high as those of high school graduates.

The rising cost of children is a significant factor in the broad decline of fertility rates across the industrialized world, and one reason why government policies aimed at encouraging women to have more babies have been largely unsuccessful. Since 1960, Canada’s fertility rate—the number of children a woman can expect to have over her lifetime—has dropped from 3.81 per woman to 1.63. “If economic factors were decisive, no one in modern societies would have any children,” wrote American demographer Kingsley Davis in the forward of The Cost of Children in the Urban United States, the seminal 1976 study that first pegged the cost of raising a child to 18 at three times the average middle-class income. That has only gone up as child-related expenses have risen faster than both wages and inflation. According to the World Values Survey, conducted by social scientists, Canadians typically say they want one more child than they actually end up having, with money as the top reason for the difference.